The present invention relates to the catalyzed reaction of an isocyanate compound and an active hydrogen compound and more particularly to a new catalyst salt useful in such catalyzed reaction.
Reaction Injection Moldings (RIM) of urethanes basically consist of a polyol and a polyisocyanate, usually with an extender (e.g. a glycol or a diamine), optionally with a blowing agent (e.g. air), optionally reinforcing material (e.g. glass, mica, etc.), wetting agents, and the like, which materials are high pressure injected through a mixing head into a pre-heated mold with usual post-molding baking thereafter applied. RIM urethanes can range from low modulus to very high modulus material parts, foamed on the interior but with a smooth surface. RIM urethanes are capable of being made into very large one-piece parts which are very light in weight. Typical present-day uses of RIM parts include, for example, automobile parts (e.g. bumpers, air deflectors, fenders, front ends, etc.), business machine housings, ski boots, office furniture, and a wide variety of products.
When used particularly in a process known as Structural RIM (SRIM) or wet mat molding, the RIM technique is subject to additional constraints. For example, upon mixing of the polyol, polyisocyanate, and other ingredients forming the SRIM reaction mixture, it is desirable that this reaction mixture exhibit virtually no viscosity increase for a period of time followed by rapid, full cure of the reaction mixture. This controlled induction period permits long flow time through glass fiber or other reinforcement as well as provides improved fiber wet-out. A controlled induction period of 60-70 seconds is useful in a variety of commercial RIM operations. In order to achieve the controlled induction period, the catalyst activity must concomitantly be delayed. After the delay, however, very rapid catalytic activity should be exhibited for achieving rapid cure of the RIM reaction mixture.
U.S. Pat. No. 3,769,244 discloses the preparation of diaza-bicycloalkene catalysts useful in the reaction of a polyol and a polyisocyanate. Acid addition salts of the diaza-bicyclo-alkene catalysts also disclosed therein have been determined to exhibit a delay in the initiation time of the polyol/polyisocyanate reaction. Such delay in initiation also is disclosed in U.S. Pat. No. 4,582,861 utilizing certain disclosed quaternary ammonium salts. Unfortunately, these prior art catalysts exhibit delay times proportional with the pK.sub.a of the acids used in their preparation as well as prolonged cure times. Additionally, extensive post-molding baking schedules still are required.